The gadget created at USP resembles a blood glucose meter for diabetics. In contact with fruits and vegetables, it identifies the quantity of fungicide
1 hour ago
Image: Researchers Collection
Text: Maria Fernanda Ziegler | FAPESP Agency
Researchers at the University of São Paulo (USP) have developed an electrochemical sensor made from kraft paper capable of detecting the presence of pesticides in fruits and vegetables in real time. In contact with apples or cabbage for example, the sensor, connected to an electronic device, identifies the presence and measures the quantity of carbendazim fungicide – widely used in Brazil, although prohibited.
The work, supported by FAPESP through three projects (18/22214-6, 19/13514-9 It is 22/03758-0), involving groups from the Institutes of Physics (IFSC-USP) and Chemistry (IQSC-USP) at the São Carlos campus. The results were released in the review food chemistry.
“To check for the presence of pesticides in food using conventional approaches, it is necessary to grind up a sample, subject it to time-consuming chemical processes, and only then detect the substance. Portable sensors, like the one we developed for continuous monitoring of pesticide concentrations in agriculture and the food industry, eliminate the need for these complex procedures. It’s much easier, cheaper, as well as being much more reliable for a supermarket, restaurant or importer to do the verification,” he says. Osvaldo Novais de Oliveira Juniorprofessor at IFSC-USP.
The new device has high sensitivity and looks like glucometers [glicosímetro] used by diabetics. To measure the quantity of pesticide in food, the electrochemical sensor detects the presence of the fungicide and the result is accessible, in a few minutes, via a mobile application.
“In the tests we performed, the device had similar sensitivity to the conventional method. All in a faster and cheaper way,” says Jose Luiz Bott Netopostdoc and corresponding author of the article describing the development of the tool.
How it works
As Bott Neto explains, the device is essentially a paper substrate modified with carbon ink and electrochemically treated in an acidic medium to activate the carboxylic groups – allowing detection.
“We use the same system used in screen printing [estamparia de roupas] to transfer the conductive carbon ink to the kraft paper strip, creating a device based on electrochemistry. The device is made of three carbon electrodes and immersed in an acid solution to activate the carboxylic groups. In other words, oxygen atoms are added to the structure of the carbon electrode. In contact with a sample contaminated with carbendazim, the sensor induces an electrochemical oxidation reaction which allows the detection of the fungicide. Thus, the amount of carbendazim is measured via electric current,” says Bott Neto at FAPESP Agency.
To develop the device, the researchers evaluated the stability and impact of the paper structure on the construction of the sensors. “In addition to the development of the device, part of the work focused on understanding the problem of the properties of paper in the manufacture of the device”, specifies the postdoctoral fellow. Thiago Serafim Martins.
Best choice
The researchers analyzed two types of paper: kraft and parchment. Both have proven to be stable enough for building sensors. However, according to Martins, the porous nature of kraft paper provided greater sensitivity to the sensor and to the carboxylic groups formed during electrochemical activation.
He explains that making paper electrodes opens up the possibility of several applications. “There are commercial plastic or ceramic electrodes. In our work, we have managed to develop electrochemical sensors with paper, a much more malleable material, which expands its use in several areas, not only in agriculture or the food sector, but in other areas such as health. , for example,” he says. . .
The article Optimized acid-treated paper-based electrochemical sensors for detecting carbendazim on apple and cabbage skin can be read at: www.sciencedirect.com/science/article/abs/pii/S0308814623000456?via%3Dihub.